Media containment for iso-grid structure forming

ABSTRACT

A method of forming an iso-grid structure may include filling multiple pockets of the iso-grid structure with a filler material, attaching a support structure to the perimeter of the iso-grid structure, shaping the iso-grid and support structures, and removing the support structure from the iso-grid structure. The support structure may be thinned and stretched during the shaping process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a nonprovisional of, and claims priority to, and thebenefit of U.S. Provisional Application No. 61/924,580, entitled “MEDIACONTAINMENT FOR ISO-GRID STRUCTURE FORMING,” filed on Jan. 7, 2014,which is hereby incorporated by reference in its entirety.

FIELD

The present disclosure relates generally to sheet metal forming. Moreparticularly, the present disclosure relates to a system and method offorming iso-grid sheet metal using a secondary sheet.

BACKGROUND

Various aerospace components are manufactured with an iso-grid pattern.These patterns are generally produced through post-form chemicalmilling. In other instances, some success has been attained throughmachining the iso-grid pattern in a flat material and then formingpost-machining. Typically, a filler material in the iso-grid pattern maybe used to prevent pocket buckling during the forming process. A stifferfiller material is generally applied for more extreme forms. However, astiffer filler material also creates a greater opportunity for thefiller to crack and liberate during the forming process. Supportingsheets of material stock can be used to assist in retaining material andoften are pinned near the center of the part. However, this centerattachment does not ensure intimate contact of the supporting sheet andiso-grid pattern throughout the forming operation, which often leads toliberation of the filler material.

SUMMARY

In various embodiments, a method of forming an iso-grid structure mayinclude filling multiple pockets of the iso-grid structure with a fillermaterial, attaching a support structure to the perimeter of the iso-gridstructure, shaping the iso-grid and support structures, and removing thesupport structure from the iso-grid structure. The support structure maybe thinned and stretched during the shaping process.

The foregoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated otherwise.These features and elements as well as the operation thereof will becomemore apparent in light of the following description and the accompanyingdrawings. It should be understood, however, the following descriptionand drawings are intended to be exemplary in nature and non-limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures.

FIG. 1A illustrates an exploded view of iso-grid and support structuresin accordance with various embodiments;

FIG. 1B illustrates a perspective view of iso-grid and supportstructures in accordance with various embodiments;

FIG. 2 illustrates formed iso-grid and support structures in accordancewith various embodiments;

FIG. 3 illustrates a formed iso-grid structure in accordance withvarious embodiments;

FIG. 4A illustrates an exploded view of iso-grid and two supportstructures in accordance with various embodiments;

FIG. 4B illustrates a perspective view of iso-grid and two supportstructures in accordance with various embodiments; and

FIG. 5 is a flowchart of an exemplary method of forming an iso-gridstructure in accordance with various embodiments.

DETAILED DESCRIPTION

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that logical, material, and mechanical changes may be madewithout departing from the spirit and scope of the disclosure. Thus, thedetailed description herein is presented for purposes of illustrationonly and not of limitation. For example, the steps recited in any of themethod or process descriptions may be executed in any order and are notnecessarily limited to the order presented. Furthermore, any referenceto singular includes plural embodiments, and any reference to more thanone component or step may include a singular embodiment or step. Also,any reference to attached, fixed, connected, or the like may includepermanent, removable, temporary, partial, full, and/or any otherpossible attachment option. Additionally, any reference to withoutcontact (or similar phrases) may also include reduced contact or minimalcontact.

An iso-grid structure may refer to a structure comprising a pattern ofribs, such as ribs that form triangular or rectangular shapes, whichincrease the stiffness of the structure while reducing the weight.Iso-grid structures may be used in applications that use thin-walledcomponents to enhance structural integrity, such as in gas turbineengines. The application of an iso-grid structure to a thin-walledcomponent may allow for improved structural integrity without the addedweight of a thicker wall. Iso-grid structures can be formed into desiredshapes. In various embodiments, a flat material can be machined into aniso-grid structure and the iso-grid structure can be formed into adesired shape. In order to help maintain the structural integrity of theiso-grid pattern during the forming process, a filler material can fillthe pockets of the iso-grid structure. The filler material may be, forexample, a curable resin such as an epoxy resin, or an Indalloy.Furthermore, the filler material can range from softer, wax-based fillerto harder, lead-based filler, such as an Indalloy alloy. The fillermaterial provides support to the iso-grid pattern during the formingprocess. The filler material may have different hardness levels, withharder filler materials offering more support but having higherlikelihood of breaking away from a pocket of the iso-grid structure. Theharder materials are less ductile and may be more likely to hold shapecompared to softer materials.

In accordance with various embodiments and with reference to FIGS. 1Aand 1B, an iso-grid structure 101 may have a filler material located inthe pockets 102 of the iso-grid pattern, and the iso-grid structure 101can be attached to a support structure 103. As shown in FIGS. 1A and 1B,support structure 103 can be attached to the face 104 of iso-gridstructure 101 having the pockets 102, thereby providing support to thefiller material. In various embodiments, iso-grid structure 101 can havetwo support structures attached, one on either side of the iso-gridstructure. In various embodiments, both iso-grid structure 101 andsupport structure 103 are flat, or substantially flat, at the time thetwo structures are being attached. In further embodiments, iso-gridstructure 101 is in a pre-formed, non-flat shape when attached tosupport structure 103, and support structure 103 has a pre-form,non-flat shape to complement iso-grid structure 101.

In accordance with various embodiments, an exemplary method of formingthe shape of iso-grid structure 101 may comprise attaching supportstructure 103 at the perimeter of iso-grid structure 101. Iso-gridstructure 101 may be attached to support structure 103 using anattachment coupling 110. In various embodiments, attachment coupling 110may include welding, brazing, mechanically fastening (clamps, screws,and the like) and any other suitable method of attached the twostructures. As previously mentioned, both iso-grid structure 101 andsupport structure 103 are typically flat at the time of attachment toeach other at the perimeters. In various embodiments, the iso-gridstructure and the support structure are attached at the respectiveperimeters. In one variation, the edges of the iso-grid structure andsupport structure are substantially flush such that the perimeters ofthe iso-grid structure and support structure are substantially the same.In various embodiments, the edge of the iso-grid structure and/or thesupport structure can extend past the edge of the other structure. Insuch embodiments, the edge of the shorter structure may be attached tothe overlapping structure at the point of overlap. As used herein, theperimeter of a structure may refer to the outer edge or proximate theouter edge.

Furthermore, in various embodiments, the attachment at the perimeter mayinclude attachment at the entire perimeter of one the structures. Invarious embodiments, attachment at the perimeter may include attachmentat portions of the perimeter. For example, the iso-grid structure andthe support structure may be attached at 50% or more of the perimeteredge. The partial perimeter attachment may occur at opposite edges ofthe structures. The partial perimeter attachment may also occur atmultiple attachment points that have unattached portions in between.

Moreover, the attached iso-grid and support structures can be shaped orformed in a variety of ways, including using rollers, male/femaleforming dies, and other methods as would be known to one skilled in theart. In accordance with various embodiments and with reference to FIG.2, as the attached iso-grid structure 101 and support structure 103 arebent and shaped, the support structure 103 may stretch and thin duringthe forming process. In various embodiments, the support structure 103maintains an attachment to the iso-grid structure 101, thereby providingsupport to keep the filler material in the pockets of the iso-gridstructure 101. Accordingly, providing more support to the iso-gridstructure during the forming process can facilitate producing moreextreme forming profiles compared to prior art ranges. Stated anotherway, the forming process of machining the iso-grid structure and thenforming using a support structure may allow for an tighter radius ofcurvature, and can allow for the use of harder filler in comparison toprior art methods. In the prior art, bending an iso-grid structure intoa small radius of curvature is more likely to experience cracking,thinning beyond allowances, and/or wrinkling due to the material notflowing during the forming process. In various embodiments, a supportstructure coupled to the iso-grid structure and supporting the fillermaterial may facilitate forming a smaller radius of curvature in theiso-grid structure without, or to a lesser degree, the drawbacks justmentioned. The harder filler material provides more support to theiso-grid pockets during the forming process and reduces the amount ofdeformities occurring in the iso-grid pattern.

Furthermore, various embodiments and with reference to FIG. 5, a methodof forming an iso-grid structure may comprise filling multiple pocketsof the iso-grid structure with a filler material 501, attaching asupport structure to the perimeter of the iso-grid structure 502,shaping the iso-grid and support structures, wherein the supportstructure is thinned and stretched during the shaping 503, and removingthe support structure from the iso-grid structure 504. After theattached iso-grid and support structures are formed to a final position,the edges can be removed (i.e., cut-off), thereby separating theiso-grid structure 101 and the support structure 403, and leaving theiso-grid structure 101 in its desired form. The support structure can bediscarded after it has been removed. Since the support structure can bediscarded, the material of support structure can be the least expensivematerial that is suitable for the forming process. For example, suitablematerials include stainless steel and steel.

In accordance with various embodiments and with reference to FIGS. 4Aand 4B, iso-grid structure forming system may comprise an iso-gridstructure 401 may have a filler material located in the pockets 402 ofthe iso-grid pattern, and the iso-grid structure 401 may be attached toa first support structure 403 and a second support structure 405. Asshown in FIGS. 4A and 4B, first support structure 403 may be attached tothe face 404 of iso-grid structure 401 having the pockets 402, therebyproviding support to the filler material, and second support structure405 may be attached to the opposite face of iso-grid structure 401. Invarious embodiments, iso-grid structure 401, first support structure403, and second support structure 405 are flat, or substantially flat,at the time the three structures are being attached.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A method of forming an iso-grid structure, themethod comprising: filling multiple pockets of the iso-grid structurewith a filler material; attaching a support structure to the perimeterof the iso-grid structure; shaping the iso-grid and support structures,wherein the support structure is thinned and stretched during theshaping; and removing the support structure from the iso-grid structure.2. The method of claim 1, wherein the iso-grid structure has a facehaving multiple pockets, and the support structure is attached to theface of the iso-grid structure.
 3. The method of claim 1, furthercomprising attaching a second support structure to the iso-gridstructure, wherein the second support structure is attached to a face ofiso-grid structure opposite the support structure.
 4. The method ofclaim 1, wherein both the iso-grid structure and the support structureare substantially flat during the attaching.
 5. The method of claim 1,wherein the filler material is a curable resin.
 6. The method of claim1, wherein the support structure is attached to the iso-grid structureusing at least one of welding, brazing, or mechanically fastening. 7.The method of claim 1, wherein the support structure is attached to theentire perimeter of the iso-grid structure.
 8. The method of claim 1,wherein the support structure is attached to a portion of the perimeterof the iso-grid structure.
 9. The method of claim 8, wherein the supportstructure is attached to at least 50% of the perimeter of the iso-gridstructure.
 10. The method of claim 8, wherein the support structure isattached on opposite edges of the perimeter of the iso-grid structure.11. The method of claim 8, wherein the support structure is attached atmultiple attachment points of the perimeter of the iso-grid structure.12. The method of claim 1, wherein the shaping comprises an applicationof at least one of rollers and male/female forming dies.
 13. The methodof claim 1, wherein the removing the support structure from the iso-gridstructure comprises cutting off the edges of the iso-grid and supportstructures.